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Date:      Tue, 20 Mar 2018 23:08:14 +0100
From:      Andreas Scherrer <ascherrer@gmail.com>
To:        freebsd-net@freebsd.org
Subject:   Re: Multicast/SSDP not working (on VLAN interface)
Message-ID:  <a7d2a418-24d5-a1c1-2fe5-8d4bcc6c1dfc@gmail.com>
In-Reply-To: <201803192311.w2JNB5lU014039@pdx.rh.CN85.dnsmgr.net>
References:  <201803192311.w2JNB5lU014039@pdx.rh.CN85.dnsmgr.net>

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Hi

Thank you, Rodney and Ivan, for coming back to me (and so quickly).

On 20.03.18 00:11, Rodney W. Grimes wrote:

...

>> So I suspect that "something" is dropping the M-SEARCH packets for some
>> reason after they are received. And I cannot get rid of the feeling that
>> it has something to do with the fact that the incoming interface is a
>> VLAN interface...
>> My first guess, anti spoofing, seems not to be the problem (I am using
>> ipfw and "not antispoof in" but that does not seem to drop any traffic).
> 
> Are you running with "firewall_type="simple""?
> If so it is set to block all 224/4 packets, see this part
> of /etc/rc.firewall:

...

No, my firewall is made from "hand curated" ipfw rules.

And I am pretty sure (never 100%, but 99% this time), that this is not a 
firewall issue. Why?

I have the following rule that should accept traffic from my client(s) 
to 239.255.255.250:1900 in place:

   allow ip from any to not me in recv re1\*

And, when I place a rule like this just before and after that rule:

   count log ip from any to any via re1\*

I see hits before but not after the "allow" rule. Hence, the policy 
accepts the packet(s). No?

Also, just adding the route for 224.0.0.0/4, without touching the ipfw 
rules, makes things work... And I am *not* using "verrevpath" in my ifpw 
rules (I do use "antispoof", but as the packets hit the rule(s) 
mentioned above, that does not seem to be the problem).

I might give Ivan's code a try, but I am not very good at compiling and 
installing software :(

If anybody is able to provide an additional hint in the mean time, I am 
more than happy to follow up.


Best
andreas



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